Submitted to: Journal of Chemical Ecology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/16/2004
Publication Date: 7/26/2004
Citation: Robacker, D.C., Lauzon, C.R., He, X. 2004. Volatiles production and attractiveness to the mexican fruit fly of enterobacter agglomerans isolated from apple maggot and mexican fruit fly. Journal of Chemical Ecology. 30(7): 1313-1331. Interpretive Summary: Agricultural agencies worldwide keep watch over fruit growing regions for the presence of and damage caused by numerous species of fruit flies. When a pest fly is detected, measures are put into action to eliminate or control the outbreak and reduce crop losses. Although numerous strategies have been developed and are typically implemented in various regions of the world, need always exists for improvement of programs and for novel methods to attack fruit fly populations. To this end, we have been studying the natural associations between fruit flies and bacteria to determine the role bacteria play in fly biology and how we can use this knowledge to defeat fruit fly pests. One such bacterium was discovered in the habitat, food and digestive tract of the apple maggot fly of the northeastern United States. Because this bacterium is so closely aligned with numerous species of fruit flies, it seemed logical that flies may actually seek and consume the bacterium when foraging for natural food sources. We tested several strains of this bacterium for attractiveness to Mexican fruit fly, a fly that poses a constant threat to the citrus producing areas of Texas and Mexico and presents a risk to California, Arizona, and Florida from possible introduction at any time. Various strains were found to differ markedly in attractiveness due to different abilities to utilize nutrients and consequently to produce odorous chemicals attractive to the flies. Notably, one chemical produced by one of the strains made otherwise attractive chemical mixtures less attractive than expected and raised the possibility that such a chemical could be used to deter flies from ovipositing in fruit orchards treated. Other chemicals and unique mixtures of these chemicals found in bacterial odors are suggesting new blends that have potential as lures for traps. Development of better lures or repellent formulations that could be put into orchards will facilitate efforts to control damaging fruit fly species, leading to lower costs and greater profits to the citrus industry.
Technical Abstract: We investigated two strains of uricase (+)Enterobacter agglomerans, one isolated from the apple maggot fly (AMF) and one from the Mexican fruit fly (MFF), for 1) attractiveness to MFF, and 2) production of attractive chemicals. Regarding chemicals demonstrated attractive to the MFF, the MFF bacterial strain produced more 2,5-dimethylpyrazine, 2-phenylethanol and indole than the AMF strain whereas the AMF strain, but not the MFF strain produced 3-hydroxybutanone. Cell types that predominated in plated subcultures varied from batch to batch of plates resulting in variation in volatiles production, especially by the AMF strain in which indole was sometimes a major component of the odor and at other times was not detectable in the volatiles. Despite the generally greater production of attractive chemicals by the MFF strain, the AMF strain was consistently more attractive than the MFF strain, and the MFF strain was not more attractive than uninoculated control plates. Statistical analyses indicated negative correlations of attractiveness with production of indole, 2,5-dimethylpyrazine and 2-phenylethanol, and positive correlation with 3-hydroxybutanone. Results support previous findings with the Mexican fruit fly that showed that combinations of attractive chemicals sometimes are not attractive.